The invention relates to a motor vehicle battery module, in particular for an electric or a hybrid vehicle.
Electric or hybrid vehicles are increasingly coming onto the market as people become more ecologically aware. These motor vehicles have at least one battery module, which provides the electrical drive energy, as the single or an additional drive. A battery module typically consists of a plurality of battery cells, in particular prismatic or prism-shaped battery cells. During production of the battery module, the battery cells are typically adhesively bonded to one another at their surfaces and then compressed by use of pressure plates with distance control and force monitoring, so that the battery cells bear directly against one another and form a compressed battery pack. The pressure plates are then connected to tie rods, as a result of which the compressed battery pack is clamped by a circumferential frame and in this way held in the defined form.
It has been found to be disadvantageous that, in the case of the battery modules known from the prior art, it is not possible to compensate for forces which occur during operation on account of cell breathing. Furthermore, production-related component tolerances cannot be compensated for in the case of the battery modules known from the prior art.
The object of the invention is to provide a motor vehicle battery module which provides force and/or distance compensation and nevertheless allows the battery cells to be pressed.
According to the invention, the object is achieved by a motor vehicle battery module, in particular for an electric or a hybrid vehicle, having at least two battery cells, which are situated laterally next to one another and form a battery pack, and also having two pressure plates which are situated on opposite sides of the battery pack and are arranged in such a way that the at least two battery cells are arranged between the two pressure plates, as well as having at least one spacer element which has a first contact face by which the at least one spacer element can bear against a side face of an adjoining battery cell. The contact face is smaller than the side face, which adjoins the spacer element, of the adjoining battery cell, so that a portion of the side face is unsupported.
An aspect of the invention is to avoid full-surface contact and pressing of the battery cells over the entire side face in order to allow, in general, distance or force compensation. Since the spacer element does not bear against the full surface of the side face of the adjoining battery cell, only a portion of the side face is supported by means of the spacer element. By way of this portion, the force which is required for pressing is transmitted to the individual battery cells by the pressure plates, so that the compressed battery pack can be formed. The unsupported portion of the side face can, in contrast, serve to balance and compensate for forces and tolerances. This creates a spacer element which mechanically spaces apart the adjoining battery cell and, at the same time, provides non-mechanical distance and/or force compensation for the adjoining battery cell.
One aspect of the invention provides that the spacer element extends over the entire adjoining side face of the adjoining battery cell. This ensures that the spacer element is associated with the entire side face of the battery cell, as a result of which it is possible to completely space apart the adjoining battery cell.
According to a further aspect of the invention, the first contact face is formed on at least one projection on the at least one spacer element. This makes it possible to space apart the adjoining battery cell in a defined manner since, amongst other things, the contact face is defined by means of the dimensions of the projection. The contact face can also be formed by two or more projections in order to achieve more homogeneous introduction of force when pressing the battery cells.
In particular, the spacer element has a main body, wherein projections are present on opposite edges of the main body, and wherein the edges are associated with opposite end sides of the adjoining battery cell. This ensures that the spacer element makes contact with the adjoining battery cell at its end-side edges, so that force transmission takes place at the edges of the adjoining battery cell during compression of the battery cells. The adjoining battery cell can undergo the greatest possible degree of force and/or distance compensation since the projections and therefore the contact face are formed on the edge.
A further aspect of the invention provides that a hollow space is formed between the spacer element and the adjoining battery cell. The hollow space is present, for example, between the two edge-side projections, the adjoining battery cell and the main body of the spacer element. On account of the hollow space, it is possible for the adjoining battery cell to expand into the hollow space during operation of the motor vehicle battery module, as a result of which compensation of the increasing forces on account of the aging of the battery cells is possible. The hollow space into which the adjoining battery cell extends constitutes non-mechanical compensation which is not dependent on a spring characteristic curve.
Furthermore, the first contact face can be of adhesive design, in particular can be provided with an adhesive coating. This ensures that the spacer element is fixedly connected to the adjoining battery cell, so that the spacer element cannot slip relative to the adjoining battery cell.
A further aspect of the invention provides that the at least one spacer element has a second contact face which is provided on that side of the spacer element which is situated opposite the first contact face and which second contact face bears against a second, adjacent battery cell, so that the at least one spacer element spaces apart two battery cells from one another. The second contact face can be designed, in particular, like the first contact face, so that a hollow space into which the second adjacent battery cell can extend likewise forms between the second, adjacent battery cell. Therefore, two battery cells can undergo force and/or distance compensation by means of one spacer element.
According to a further embodiment of the invention, the at least one spacer element has a second contact face which is provided on that side of the spacer element which is situated opposite the first contact face and which second contact face bears against a pressure plate, so that the at least one spacer element spaces apart an end-side battery cell of the battery pack from a pressure plate. Force and/or distance compensation of the edge-side battery cell is possible in this way. In general, this results in cell breathing or expansion of the battery cells being possible during operation since the edge-side battery cell does not bear against the full surface of the pressure plate. Nevertheless, the required pressing is achieved since the pressure plate acts on the end-side battery cell, and therefore the entire battery pack, by means of the spacer element and, in particular, the projections.
In particular, the spacer element has a U- or double-T-shaped cross section. Depending on the use of the spacer element, the spacer element can be designed as a “double-T”-shaped spacer element, as a result of which two adjacent battery cells undergo distance compensation. Provided that the spacer element is arranged on a pressure plate, the spacer element can also have a U-shaped cross section, wherein the spacer element bears against the end-side or outer battery cell of the battery pack by way of the two free limbs which represent the projections.
According to one aspect of the invention, the at least one spacer element is formed from an electrically insulating material. Therefore, the spacer element provides electrical insulation of the battery cells at the same time, as a result of which the spacer element has a double function, specifically force and/or distance compensation and electrical insulation. Additional insulation between the battery cells can therefore be dispensed with, as a result of which the number of components in the motor vehicle battery module is reduced.
A further embodiment of the invention provides that at least one spacer element is provided between a plurality of, in particular all of, the adjacent battery cells and/or between the outer battery cells and the adjacent pressure plates. This forms force and/or distance compensation of all of the battery cells, as a result of which it is ensured that the increasing force can be adequately compensated for over the run time of the battery module on account of the expansion of the battery cells.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.